1. Technical Field
This invention relates to a driver operating in a firmware environment. More specifically, the driver manages launching of tasks at different priority levels while maintaining a predetermined level of operation.
2. Description of the Prior Art
Firmware is software that is stored in hardware, such that the software is retained even after power to the hardware ceases. At boot time, the firmware of a computer or computer system stores and uses information describing a computer's processors, nodes, memory and other devices. The firmware operates on a parallel platform to the operating system.
In prior art computers, the firmware enabled system interrupts to occur in order to launch different applications at different priority levels. The prior art systems require a greater amount of functionality to accommodate system interrupts. Some firmware interface environments disable system interrupts to reduce the amount of functionality required to operate the machines in the system. The Intel Extensible Firmware Interface (EFI) is one firmware environment which reduces functionality required to operate the machine by disabling interrupts. In addition to disabling system interrupts, tasks within the EFI may temporarily increase their priority level of operation, but they are not allowed to decrease the priority level. Accordingly, tasks operating within the EFI environment, or similar platforms, are not permitted to execute system interrupts to execute tasks that may be operating at different levels of priority and may increase priority levels.
There are two types of operating programs within the EFI: a driver and an application. The driver provides a set of resources, i.e. programming interfaces. Once a driver is loaded within the firmware environment, it remains in the system for future application. The driver is not permitted to load other drivers after its initialization has completed. In addition, the EFI also prohibits the ability to load applications from a resident driver. An application is an executable program that is loaded, executed and expires. During run time, the application can load other drivers and applications. Accordingly, the application is executed for loading a driver to operate within the firmware environment and within the protocols of the system.
There is therefore a need to launch a driver that will prioritize execution of different priority levels of tasks within the confines of the EFI firmware environment. The driver must be launched by an application that will allow it to remain resident within the firmware and will provide all the required protocols for operating independently and without the need to launch secondary drivers. Accordingly, it is desirable to design a driver that will allow lower priority level applications to be launched without executing a system interrupt and without changing the priority level of a higher level application already in use.